A large-scale, longitudinal, study found that less than seven percent of cancer patients received germline genetic testing, even though it is recommended by practice guidelines to support targeted treatment and inform health decisions by relatives. The authors, who included researchers from Stanford and University of Michigan, noted that genetic testing rates increased over time, but even in 2021 rates in this population were far lower than what was recommended.
The data for the study came from the Surveillance, Epidemiology, and End Results registries on patients 20 years or older diagnosed with cancer between 2013 and 2019. Almost 1.4 million patients from California and Georgia were included.
“Because clinical trials have demonstrated that germline-directed cancer screening, preventive surgery, and targeted therapies can improve survival, low rates of germline genetic testing may contribute to higher rates of cancer mortality,” the authors write.
The paper appears this week in JAMA online. The lead author is Allison W. Kurian, MD of the Stanford University School of Medicine.
It’s estimated that 10% of cancer patients have a germline risk variant. The most common are mutations in BRCA1 and BRCA2, which are associated with an increased risk of breast, ovarian, pancreatic, and prostate cancer. Also common are germline variants in MLH1, MSH2, MSH6, and PMS2 (Lynch syndrome), which are associated with colorectal, endometrial, and other cancers.
In this study, of all pathogenic results, 67.5% to 94.9% of variants were identified in genes for which practice guidelines recommend testing and 68.3% to 83.8% were identified in genes associated with the diagnosed cancer type.
Only 6.8% (n+93052) of patients were tested within two years of cancer diagnosis. The highest level of testing occurred in men with breast cancer (50%) and ovarian cancer patients (38.6%).The proportion of patients tested varied widely by cancer type: 26% for female breast cancer patients, 7.5% for patients with multiple cancers, 6.4% for endometrial cancer, 5.6% for pancreatic, and just 0.3% for lung cancer.
There was also variation according to race, as 31% of non-Hispanic White patients with male breast cancer, female breast cancer, or ovarian cancer underwent testing. But patients of other races and ethnicities underwent testing less often: 22% of Asian patients, 25% of Black patients, and 23% of Hispanic patients.
In an accompanying editorial, Zsofia K. Stadler, MD, and Devorah Schrag, MD, MPH, write “Genetic testing for inherited cancer syndromes has become an integral component of cancer care because it directly affects management and therapy.”
They point out that in 2014, the first poly(adenosine diphosphate–ribose) polymerase inhibitor was approved by the U.S. Food and Drug Administration (FDA) for BRCA-associated ovarian cancer, and more recently approval has been expanded to include treatment for BRCA-associated breast cancer, pancreatic cancer, and prostate cancer.
Practice guidelines now recommend testing for inherited cancer susceptibility genes for all patients with ovarian, male breast, and pancreatic cancer.
As Stadler and Schrag write: “For other cancer types, including female breast, prostate, and colorectal, the criteria for testing have expanded, with more practice guidelines now advocating for genetic susceptibility testing for all patients or increasing subsets of patients.”
In addition to guiding treatment, a positive BRCA1 or BRCA2 result may choose to undergo preventive mastectomy or salpingo-oophorectomy. Also, patients with high-risk variants may also be recommended for more frequent or intensive cancer screening.
